Strand and Cable R&D

1. Strand and Cable R&D D. Turrioni, Fermilab 1st FNAL-CERN Collaboration Meeting Fermilab, May 13, 2011

2. Outline • Cable and Strand Specifications • Cabling machine, tooling and instrumentation • Cable study and development • QA/QC • Summary Strand and Cable

3. Cable Specification • The large aspect ratio of the cable and the present cabling procedure require the cable fabrication in two stages: the rectangular cable with narrower width and lower packing factor and the keystone cable with final parameters • Long Unit Length ~ 210 m Strand and Cable

4. Strand Specification • Nb3Sn RRP-108/127 strand produced by Oxford SC Technology • Relatively Stable Strand@ 4.5 K and 1.9 K • High Jc Strand and Cable

5. Cabling Machine • Compact machine. • Two major upgrades : • Continuous cable pitch regulation with the electronic synchronization of the main wheel and the caterpillar motion • 42-spool wheel • Max Speed of 5 m/min Respooler Strand and Cable

6. Cable Forming Fixtures Turk head Keystoning Tooling Side Rollers and Mandrels Strand and Cable

7. Instrumentation Turk head Mitutoyo Dial Indicator ( 1 µm resolution ) • Measurements of the two dial indicators are acquired every 3 cm at 1 m/min of production speed. MitutoyoDigimatic Multiplexer MUX-10 Keystoning tooling Dial Indicator ( 1 µm resolution ) Mitutoyo Micrometer ( 1 µm resolution ) PC Strand and Cable

8. Cable Measurements 40 Strands cable for practice coil Strand and Cable

9. Cable development • Design and parametric considerations were used in the development of the cables to be made of Nb3Sn RRP wires. • For the cable geometry contemplated by the magnet designers the mandrel was designed in order to provide sufficient room for the strands to wind around it without excessive damage. • This requirement, which accompanied the requisites for mechanical stability, allowed determining quite accurately the number of strands needed for each cable geometry. Strand and Cable

10. Cable Design Parameters • The geometrical relationship between a cable of desired width wC, to be obtained with strands of diameter d, and the required mandrel width wm is shown in the first expression below where  is an empirical factor determined by experiment. • The second expression is a simplified formula used for the purpose of parameterizing the number of strands needed for each cable geometry. N is the number of strands in the cable,  the cable lay (or pitch) angle ≥ 1 A large body of data acquired during Nb3Sn conductor development shows that when cabling Nb3Sn RRP wires, it is important that: TD-10-022 “Nb3Sn Cable Development for the 11 T Dipole Program” Strand and Cable

11. 40 Strands Cables List • Next slides show results of: • Five Rectangular copper practice cables with and without core • Two rectangular Nb3Sn practice cable with and without core (108/127 strand design) • One Keystoned Nb3Sn practice cable without core (114/127 strand design) a Rectangular cable has been annealed in Argon at 180 Cº for 1 hr b Stainless steel core used was 9.525 mm x 25 mm in size. Strand and Cable

12. Cable development Rectangular Copper Cables • The first forming step of the rectangular cables to be used to produce keystoned cables 14.7 mm (with 40 strands) and 15.1 mm (with 41 strands) wide was finalized out of hard Cu wires of 0.7 mm nominal diameter. • The rectangular cables were 1% narrower than the final desired widths of the keystoned cables in order to account for the 1% width expansion to be expected when performing the second, keystoning, cabling step. • Selected design was the 40 strand cable because of CERN cabling machine capability a Stainless steel core used was 9.525 mm x 25 mm in size. Strand and Cable

13. Cable development Rectangular Nb3Sn • To verify the impact of the cabling process on the actual superconductor that will be used in the magnet short model two 40 strands superconducting cables were produced. • Strand design RRP 108/127, 0.7 mm • The appropriate electrical and microstructural characterizations were done a Stainless steel core used was 9.525 mm x 25 mm in size. Strand and Cable

14. Damage Analysis • 6 cross sections of each cable (with and without core) are studied. • Both cables show very little internal damage. • These cables show less than average strand damage. Cable cross section with core Damage Details Strand and Cable

15. Electrical characterizationRectangular with core In VI Tests, solid markers stands for Iquenchevaluated from full transition, whereas empty markers stands for the maximum current reached by sample before quench with no visible transition. Strand and Cable

16. Electrical characterizationRectangular without core In VI Tests, solid markers stands for Iquenchevaluated from full transition, whereas empty markers stands for the maximum current reached by sample before quench with no visible transition. Strand and Cable

17. Keystoned cables • After the first stage of rectangular cable study was completed and the new rollers for the keystoning fixture commissioned the second stage was to make keystoned cables. • The attempt to make in a single pass a keystoned copper cable was not completely successful. The cable formed but roped entering the keystone wheels in the first 80m. • The decision was to finish the remaining 245m rectangular and to make a second rectangular copper cable to be wound in a practice coil. Strand and Cable

18. Rectangular Copper Practice Cable #2 • Cable was fabricated for winding a practice coil. • Cable was well formed and to size Left Side view Right Side view Top view Strand and Cable

19. Keystoned Nb3Sn cable • Nb3Sn Keystoned 40 strands cable was made in two passes. • 114/127 Strand design • The cable strands diameter except one was originally 1 mm drawn to 0.7 mm. • In the first pass 250 m of rectangular cable was made. • A piece of 15 m of the rectangular cable was cut and annealed in argon atmosphere for 1 hour at 180 ºC. • The two cables , annealed and not, were keystoned. • Microstructural analysis of cable cross sections and electrical characterization of extracted samples were performed. Keystoned no annealed RRP 114/127 Keystoned annealed a Rectangular cable has been annealed in Argon at 180 Cº for 1 hr Strand and Cable

20. Damage AnalysisNb3Sn KS Cable Rectangular • Several cross sections from keystoned, rectangular, keystoned annealed, reacted and unreacted cable were analyzed. Keystoned Rectangular Reacted Keystoned reacted Keystoned Annealed Reacted Rectangular cable edges Strand and Cable

21. Damage AnalysisNb3Sn KS Cable (cont’d) a Rectangular cable has been annealed in Argon at 180 Cº for 1 hr • 6 cross sections of each Type (Rectangular, Keystoned, Keystoned annealed) are studied. • Keystoned cable shows an average strand damage. • The annealed cable shows less than average strand damage. Strand and Cable

22. Electrical characterizationNb3Sn KS Cable In VI Tests, solid markers stands for Iquenchevaluated from full transition, whereas empty markers stands for the maximum current reached by sample before quench with no visible transition Strand and Cable

23. Cable Readiness Review • An internal readiness review of the 11 Tesla dipole cable was held on May 02, 2011. • The following aspects were reviewed: • Procedure • Documentation (Traveler, Logbooks) • Infrastructures (Cable Machine, Tooling) • Overall their were no major or minor findings • Starting cable fabrication for the demonstrator coils Front page of the cable traveler Strand and Cable

24. Cable Map • 1 UL→ 210 m • 3 UL for a long cable + 1 UL + 60 m for the analysis • Cable fabrication for 11T Demo Coils in progress Strand and Cable

25. Summary • Cable has been designed • Technology developed and experiments verified • Reviewed • Cable Fabrication in progress Strand and Cable

26. R&D steps • Fabrication and test of Cored Cables • Longer UL (650 m) for 5.5 m long coil • New Strand Design • RRP-151/169 from OST • R&D strand from Hyper Tech, Inc. • PIT strand from CERN Strand and Cable